Vol.23,

An optimization analysis for finite element (FE) results by variance analysis method (VAM) of orthogonal array designs (OADs) was performed to improve the dynamic performance of the prototype magnet girder assembly (MGA) in the storage ring of the Shanghai Synchrotron Radiation Facility (SSRF). Seven factors were considered. The analyses show that the most important factor for the first eigenfrequency is stiffness of the support systems, and the main factor resulting in the relatively low first eigenfrequency of the MGA is its weak support systems. From the OADs optimization analysis, mechanical design of the MGA was improved, and its dynamic performance was improved obviously.

401

In the 3^rd generation synchrotron light source, beside the orbit, air disturbance and ground vibration also could affect the position stability of photon beam in synchrotrons radiation measurement. In the condition of implementation of orbit feedback system at SSRF, the measured position stability of photon beam in synchrotrons radiation measurement station was presented in this paper. And then the improvement methods of position stability of photon beam were discussed. Finally the measured result was shown when the designed feedback system is implemented to improve the position stability of photon beam.

431

Imaging blood vessels is of importance for determining the vascular distribution of organs and tumors. Phase-contrast X-ray imaging can reveal the vessels in much more detail than conventional X-ray absorption method. Visualizing murine liver microvasculature ex vivo with phase-contrast X-ray imaging was performed at Shanghai Synchrotron Radiation Facility. Barium sulfate and physiological saline were used as contrast agents for the blood vessels. Blood vessels of <Φ20 μm could be detected by replacing resident blood with physiological saline or barium sulfate. An entire branch of the portal vein (from the main axial portal vein to the ninth generation of branching) could be captured in a single phase-contrast image. It is demonstrated that selective angiography based on phase contrast X-ray imaging, with a physiological material of low Z elements (such as saline) being the contrast agent, is a viable imaging strategy. Further efforts will be focused on using the technique to image tumor angiogenesis.

598

Output voltage is an important performance characteristic of planar insulating core transformer (PICT). In PICT magnetic cores are insulated from their neighboring magnetic cores by solid insulating materials. Solid insulating materials can increase leakage flux. This results in a low generated voltage in secondary coils, especially on the upper stages. Connecting flux compensation capacitors to secondary coils can compensate the flux loss. Design equations to calculate the flux compensation capacitors value and relevant simulation by CST and Protel software were presented. Simulation results of an actual PICT showed that output voltage increased by 19% after being connected to flux compensation capacitors and the voltage on every stage was equally distributed. Results of simulation were consistent with the following experimental test, which revealed that flux compensation capacitors were effective.

539

A sensitive and accurate method for determining ultra low-level ²¹⁰Pb and ²¹²Pb in water samples through double measurements was developed. Pb was pre-concentrated as hydroxides, separated from alkaline earth elements as PbS precipitate, purified by an anion exchange resin chromatography column, precipitated as PbSO₄ for source preparation and counted by a low background β-counter. The procedure was checked with IAEA reference materials, and the results agreed well with the recommended values. The minimum detectable activity was 0.062 mBq·L^–1 for ²¹⁰Pb and 0.053 mBq·L^–1 for ²¹²Pb with a 48 L water sample. Seventeen drinking water samples were analyzed, with a Pb recovery of 88.8±5.5%, and the typical activity concentrations were 0.191−15.1 mBq·L^–1 for ²¹⁰Pb and of 1.12−5.77 mBq·L^–1 for ²¹²Pb. The estimated committed effective doses to adult members of the public in Italy due to intake of ²¹⁰Pb and ²¹²Pb in drinking water were 0.096−7.59 μSv·a^–1 and 0.005−0.025 μSv·a^–1, respectively.

452

Irradiation treatment of sewage sludge was carried out using an electron beam accelerator. The effects of irradiation dose, sludge water content and sludge thickness on the breakdown of sludge flocs, thus the formulation of soluble chemical oxygen demand (SCOD) and soluble total nitrogen (STN) , and the reduction of MLSS and endogenous OUR, and so on, were investigated. It was observed that, with increased doses, the SCOD, STN and UV absorption intensity of the sludge supernatant increased rapidly with similar trends, and MLSS considerably decreased, all indicating that a large amount of the cell contents of sewage sludge were released by electron beam irradiation. The results of endogenous OUR also showed that a large number of microorganisms in sewage sludge were killed or deactivated. Zeta potential sludge became more positive with increased doses, implying that the dewatering performance of sewage sludge was not adversely affected. It was also found that the thickness of sludge was an operation parameter of great importance in the electron beam treatment of sewage sludge due to the relatively short penetration depth in water/sludge of the high-energy electrons.

469

Phage display technique provides a powerful approach for the discovery of new tumor-specific peptides. However, the peptides isolated through this technique usually did not possess high tumor-specific property. A pre-clearing step was introduced to increase the efficiency of biopanning by removal of particles that could interact with ubiquitously expressed cellular receptors in the non-target organs. The randomized Ph.D-CX₇C phage library (Phage III) was first pre-cleared in normal mice to reduce vasculature- or organ-targeting phages to get the pre-cleared phage library, and then the tumor-targeting bacteriophage particles (Phage I) were screened from pre-clearing phage library in S180 tumor-bearing mice. The biodistribution results of ^99mTc-labeled phages in mice bearing S180 tumor show that the uptake of ^99mTc-labeled Phage I in tumor is high but low in normal organs, and the tumor-to-liver and tumor-to-spleen ratios of ^99mTc-labeled Phage I are higher than those of ^99mTc-labeled Phage II (tumor-specific phages screened from the original CX7C library) and Phage III (unscreened phages from the original CX7C library). It indicates that the yield of tumor-targeting bacteriophage particles could be improved and the non-specific binding in organs becomes weak. Consequently, the pre-clearing phage display method could improve the yield of positive hits by reducing the non-target organ accumulation of bacteriophage particles.

507

This work was to develop a semi-automated synthesis of ¹⁸F-9-fluoropropyl-9-desmethyl-DTBZ (¹⁸F-FP-DTBZ) and validate its potential as a vesicular monoamine transporter 2 (VMAT2) ligand. ¹⁸F-FP-DTBZ was synthesized by a semi-automated procedure in a 21–35% yield without decay correction and with a radiochemical purity of >98%. Bioistribution in rats exhibited a favorable brain uptakes of the ligand (0.31±0.04 ID% at 60 min post injection, n=8). The highest radioactivity located in VMAT2 enriched striatal tissue. The target-to-nontarget ratio (striatum/cerebellum, ST/CB) was 4.81±0.84. Blocking studies implied that striatum uptake could be blocked by DTBZ (a VMAT2 inhibitor) but could not by CFT (a dopamine transporter inhibitor). MicroPET imaging with ¹⁸F-FP-DTBZ in normal rats gave high quality images in which high radioactivity were observed in the striatal tissue. Time-and-activity curves revealed good retention in the target (striatum) and rapid clearance in the background (cerebellum), which resulted in a maximum ST/CB ratio of 5.08±0.81 (n=3) in 80–120 min. By contrast, the 6-hydroxydopamine unilateral lesioned rats gave asymmetrical striata images with higher ¹⁸F-FP-DTBZ concentration on the unlesioned side (unlesioned-ST/CB=5.21±0.38, n=3) than the lesioned (lesioned-ST/CB=2.34±0.51). The results validated that ¹⁸F-FP-DTBZ is a favorable PET ligand binding to VMAT2.

451

Integrin α_vβ₃, a cell adhesion molecule, plays a key role in angiogenesis and tumor cell metastasis and is therefore an important target for new therapeutic and diagnostic strategies. Since RGD bind to α_vβ₃ particularly, a lot of RGD containing peptides were radiolabeled and evaluated as imaging or therapeutic agents. In this study, a new ¹⁸⁸Re-RGD peptide analog was synthesized and characterized. Within 30 min, the ¹⁸⁸Re-H-E[c(RGDyK)]₂ was obtained in radiochemical purity of better than 95%. The His-E[c(RGDyK)]₂ had a good integrin-binding affinity (50% inhibitiory concentracer (IC₅₀=46.5×10^–9 nm) and exhibited active accumulation (7.20±1.06) in S180 tumor. Because of relatively fast washout in blood and normal tissues, the target/non-target ratio was high. Further experiments to improve the tumor targeting efficacy and in vivo kinetic profiles are in progress towards developing it into a promising radio agent.

440

In this work, a calculation method of chemical kinetics was established for labeling reaction of ^99mTc-N-ethyl-N₂S₂-memantine, a potential NMDA receptor imaging agent prepared in our laboratory. Four groups of vials (3 vials per group) were added with 0.02 mL (1 mg/mL) N-ethyl-N₂S₂- Memantine, 0.08 mL (40 mg/mL) GH, 0.05 mL (10 mg/mL) EDTA-2Na, 0.035 mL (2 mg/mL) SnF₂, 0.8 mL phosphate buffer(1 mol/L, pH 6.5) and 37 MBq Na^99mTcO₄. The vials were incubated at 70°C, 80°C, 90°C or 100°C. Samples were taken with capillary from the vials at 2, 5, 10, 20, 30, 40 and 60 min. Labeling yields were determined by TLC. Order of reaction n, rate constant k, activation energy E_a and half life t_1/2 of labeling reaction were calculated with the kinetics software we compiled. Mean labeling yields of ^99m Tc-N-ethyl-N₂S₂-memantine at 2, 5, 10, 20, 30, 40 and 60 min were (1) 13.5, 15.7, 34.0, 64.8, 81.9, 91.4 and 95.4 at 70°C; (2) 13.2, 20.5, 40.1, 70.0, 88.2, 94.5 and 95.6 at 80°C; (3) 15.6, 22.9, 43.7, 74.3, 87.2, 93.4 and 96.1 at 90°C; and (4) 20.5, 25.8, 45.3, 81.1, 92.2, 95.6 and 96.0 at 100°C. The other parameters were; n =1; k=0.053, 0.061, 0.063 and 0.076 L/min at 70°C, 80°C, 90°C and 100°C, respectively; E_a=12.38 kJ/L^; t_1/2=13.11, 11.45, 11.05 and 9.07 min at 70°C, 80°C, 90°C and 100°C, respectively. The mean labeling yield increased with temperature and time, optimized at 100°C and 40–60 min. The concentration of ^99mTc-N-ethyl-N₂S₂-Memantine was larger than that of Na^99mTcO₄, so n=1. The k increased with reaction, hence the accelerated reaction rate at higher temperatures. The labeling reaction was not so difficult because of the low E_a. The t_1/2 decreased with increasing reaction temperature, hence the acceleration of labeling reaction.

399

The channeling phenomenon of carbon ions in single-wall carbon nanotubes (SWCNTs) is investigated by using the molecular dynamics simulation with analytical potentials. The relationship between the channeling critical angles in the SWCNT and the bonding interaction is analyzed. It was found that, at 200–5000 eV and 10°–20° of incident angle, the ions with the bonding interaction or chemical effect, have decreased dechanneling probabilities and increased critical angles, compared to that of non-bonding ions. So the bonding effect cannot be ignored in the channeling mechanism of carbon ions through a SWCNT.

398

The heavy-ion phase-space exploration (HIPSE) model is used to discuss the origin of the nuclear spin in intermediate energy heavy-ion collision (HIC). The spin of maximal projectile-like fragment is found to depend strongly on impact parameter of a reaction system, while it relates weakly to the collision violence. Some interesting multi-fragmentation phenomena related to the spin are shown. We also found that the excitation energy in the de-excitation stage plays a robust role at the de-excitation stage in HIC.

415